In recent years, because of diversification in design, improvement in strength of a can barrel with a decrease in thickness of a can barrel or for other reasons, a can of which the can barrel has been processed (embossed) to have convex parts and/or concave parts thereon (embossed can) has been developed and put on the market.
If processing is conducted such that convex parts and/or concave parts are formed so as to conform to patterns, characters or the like (hereinafter, they are named generically as “patterns” in this specification) which have been printed on a can barrel, the design of the can body is enhanced. Therefore, processing has been conducted to form concave parts and/or convex parts in at least part of a pattern such that they conform to the pattern.
In general, an embossed can means a can which is shaped while being so positioned to a prescribed design (including a design composed of concave parts and/or convex parts, with no pattern being printed).
For example, Patent Document 1 discloses a technology of a can characterized in that a pattern is printed on the outer peripheral surface of a can barrel and at least part of the pattern is processed to have convex parts and/or concave parts so as to be positioned to the pattern, and two or more positioning marks for positioning the pattern to a predetermined position are formed on the outer peripheral surface.
Further, Patent Document 2 discloses a technology of a method for producing an embossed can body in which a pattern is printed on the outer peripheral surface of a cylindrical can barrel, and, at least part of the pattern is subjected to embossing to have convex parts and/or concave parts so as to be positioned to the pattern, wherein a plastic processing step of forming a plastically deformed part by conducting deformation processing on the part of outer surface of a can barrel is provided prior to an embossing processing step in which positioning to a pattern is conducted and convex parts and/or concave parts (embossing) are formed.
Patent Document 3 discloses a method of processing a can barrel in which predetermined processing is conducted on a barrel of a can body having a barrel and a bottom provided on the one side of this barrel, wherein a stopping mark is provided on the downstream side of the rotation direction and a confirmation mark is provided on the upstream side of the rotation direction are provided on the barrel as positioning marks, a conformation sensor is provided on the upstream side of the rotation and a stopping sensor is provided on the downstream side of the rotation in the positioning step for conducting rotational positioning, when the stopping mark is detected by the confirmation sensor, the rotation of the can barrel is slowed down and, when the stopping mark is detected by the stopping sensor, the can barrel is stopped, and when the rotation of the can barrel is stopped, it is determined whether the rotational positioning of the can barrel is accurately conducted or not by whether the confirmation mark is detected by the confirmation sensor or not.
Further, Patent Document 4 discloses a technology of positioning a printed design of a can barrel in which, before a can barrel is processed in conformity to a design which has been printed on the outer surface of the can barrel beforehand, respective cans which are continuously transferred in the state that the printed design is positioned at a random position are rotated in the circumferential direction of the can barrel at a high speed and then a can rotation speed is lowered at the timing when a large mark printed on the can barrel is detected by a sensor, successively, rotation of the can is stopped when a small mark printed on the can barrel is detected, whereby positioning of the printed design is conducted.